Multi-piece solid golf ball

Abstract

In a multi-piece solid golf ball made up of, successively, a core, an intermediate layer and a cover having numerous dimples on the surface thereof, the intermediate layer is formed of a resin material and the cover is formed of a urethane resin material, each having a specific respective Shore D hardness. The ball has a specific (intermediate layer thickness)/(core diameter) value and a specific (cover thickness)/(core diameter) value, and the core has a specific deflection. The sphere consisting of the core encased by the intermediate layer has an initial velocity A and the core has an initial velocity B which together satisfy the condition A−B≥0 m/s. This golf ball provides an increased distance and has both a soft feel when played and a high durability to repeated impact.

The invention claimed is: 
     
       1. A multi-piece solid golf ball comprising a core, an intermediate layer encasing the core and a cover which encases the intermediate layer and has numerous dimples formed on an outside surface thereof (ball surface), wherein the intermediate layer is formed of a resin material, the cover is formed of a urethane resin material; the intermediate layer has a material hardness on the Shore D hardness scale of from 61 to 70, the cover has a material hardness on the Shore D hardness scale of 55 or less, the (intermediate layer thickness)/(core diameter) value is from 0.025 to 0.041, the (cover thickness)/(core diameter) value is from 0.014 to 0.024, the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) of at least 4.2 mm, and the sphere consisting of the core encased by the intermediate layer (intermediate layer-encased sphere) has an initial velocity A and the core has an initial velocity B which together satisfy the condition A−B≥0 m/s, and wherein the core has a hardness profile from a center to a surface thereof which satisfies the following condition,
   (JIS-C hardness at core surface−JIS-C hardness 5 mm inside of core surface)−(JIS-C hardness 5 mm outside of core center−JIS-C hardness at core center)≥0.
 
 
     
     
       2. The multi-piece solid golf ball of  claim 1 , wherein the core has a center and a surface such that the value obtained by subtracting the JIS-C hardness at the core center from the JIS-C hardness at the core surface is at least 15. 
     
     
       3. The multi-piece solid golf ball of  claim 1 , wherein the core has a hardness profile from a center to a surface thereof which satisfies the following condition:
   (JIS-C hardness at core surface−JIS-C hardness 5 mm inside of core surface)−(JIS-C hardness 5 mm outside of core center−JIS-C hardness at core center)≥2.
 
 
     
     
       4. The multi-piece solid golf ball of  claim 1 , wherein the core has a hardness profile from a center to a surface thereof which satisfies the following condition:
   (JIS-C hardness at core surface−JIS-C hardness 5 mm inside of core surface)−(JIS-C hardness 5 mm outside of core center−JIS-C hardness at core center)≥5.
 
 
     
     
       5. The multi-piece solid golf ball of  claim 1 , wherein the (intermediate layer thickness)/(core diameter) value is from 0.028 to 0.041 and the (cover thickness)/(core diameter) value is from 0.017 to 0.024. 
     
     
       6. The multi-piece solid golf ball of  claim 1 , wherein the value obtained by subtracting the Shore D hardness at a surface of the core from the Shore D hardness at a surface of the intermediate layer-encased sphere is at least 6, the value obtained by subtracting the Shore D hardness at the surface of the intermediate layer-encased sphere from the Shore D hardness at the ball surface is 0 or less, and the value obtained by subtracting the Shore D hardness at the ball surface from the Shore D hardness at the core surface is −5 or more. 
     
     
       7. The multi-piece solid golf ball of  claim 1 , wherein the initial velocities of the core, the intermediate layer-encased sphere and the ball satisfy the following relationship:
 initial velocity of intermediate layer-encased sphere initial velocity of core>initial velocity of ball. 
 
     
     
       8. The multi-piece solid golf ball of  claim 1 , wherein the dimples formed on the ball surface are of at least three types of differing diameter or depth or both, the total number of dimples is from 250 to 380 and the dimple surface coverage SR, defined as the proportion of the ball surface accounted for by the total surface area of the hypothetical spherical surfaces circumscribed by the edges of the individual dimples, is at least 70%.